Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare openWorldHint=true and non-idempotent behavior, and the description adds genuinely new context: the event is signed and no delivery record is persisted. That side-effect disclosure is exactly what an agent needs before triggering an outbound call, though it doesn't mention failure modes when no URL is configured.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two short sentences, zero filler, with the core action front-loaded and the side-effect caveat immediately after. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter tool with no output schema, the description covers what is sent, where it goes, and what is not recorded. The only gap is behavior when no webhook URL exists or when the endpoint fails, which an agent would want to know before calling.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters and the description correctly implies no input is needed; nothing is required from the caller beyond the tool invocation. Baseline 4 applies for a parameterless tool.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('POST a signed webhook.test event to the saved URL'), so the agent knows exactly what action is taken and what receives it. It doesn't explicitly name the sibling `set_webhook` that establishes the saved URL, leaving sibling differentiation implicit rather than stated.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The phrase 'to the saved URL' implies a prerequisite (a webhook must already be configured via set_webhook) and implies this is a diagnostic tool, but the description never states when to use this versus set_webhook, nor what to do if no URL is saved. Usage is inferable but not spelled out.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.